The present invention relates to the field of multi-media recording and playback. More specifically, the present invention relates to reducing tune-time delay in a personal versatile recorder subsystem of a television appliance.
Cable and satellite television systems are capable of providing a viewer with hundreds of channels of television programming. Such an abundance of programming often creates difficult viewing choices for a viewer when two programs that the viewer would like to watch are broadcast simultaneously. In addition, a viewer may like to record for later viewing a program which is broadcast at an inconvenient time.
These problems were first overcome by recording devices such as the video cassette recorder (VCR). A VCR allows a viewer to record incoming audiovisual programming while viewing a different channel. A VCR also allows a viewer to record programming while the viewer is unavailable to watch the programming by presetting program times into the VCR. Thus the VCR allows a viewer to record and view programming that the viewer would otherwise not be able to view.
The VCR concept has been expanded in recent years to include digital compression devices that provide additional features for managing the reception and recording of analog audiovisual programming. Such products have been given various names, such as personal video recorders, video recording computers, and personal television servers (hereinafter “personal video recorders”). Current examples of personal video recorders include the TiVo® system made by TiVo, Inc. and the ReplayTV® system made by Replay Networks, Inc. Personal video recorders replace the conventional VCR magnetic tape recording medium with a computer hard drive internal to the recorder. The personal video recorder is connected between a viewer's television set and set-top terminal, satellite receiver, or antenna. The personal video recorder can control the channel tuned on the television, provide an interactive electronic program guide, and record programming on a manual, external signal responsive, or timer controlled basis. Additionally, the personal video recorder can buffer incoming audiovisual programming to enable a viewer to pause or replay a portion of a live television program, so long as the pause or replay does not exceed the capacity of the buffer. The personal video recorder can alternatively be built into the set-top terminal or the television, instead of comprising a separate stand-alone box.
However, the prior art personal video recorder does not have the capability to store and replay other types of media, including Internet data files such as web pages, MP3 files, JPEG files, bit map files, and the like. In addition, the prior art personal video recorder does not have the capability to store, retrieve and replay streamed audiovisual digital programming content from the Internet or other caching servers.
The personal versatile recorder (PVR) developed by General Instrument Corporation of Horsham, Pa., the assignee of the present invention, overcomes the disadvantages of the prior art personal video recorders. One implementation of a PVR is described in U.S. patent application Ser. No. 09/520,968, filed on Mar. 8, 2000, entitled “Personal Versatile Recorder and Method of Implementing and Using Same.” The PVR enables the receipt, recording, retrieval and playback of a variety of types of data or data files on a hard drive, including but not limited to digital and analog audiovisual programming, streaming media, picture files, video files, audio files, Hypertext Markup Language (HTML) files, and various types of Internet multimedia content.
In a typical PVR application, the incoming analog video is converted into MPEG format and the resulting digital data is routed through the hard disk drive of the PVR in order to enable any “trick play” modes such as instant replay, slow play, rewind, or pause. However, due to the bursty nature of the hard disk drive transfers, buffers are required at both the read and write ports of the hard disk drive. The resultant latency through both buffers and the hard disk may be as much as two seconds. Such a delay occurs each time a new channel is tuned and is apparent to the consumer. Where a digital channel is used as the input, the PVR delay will be added to the tuning delay, also resulting in an intolerable delay for each channel change. If the PVR delay is eliminated by bypassing the PVR subsystem, the input video is not capable of being recorded and the trick play modes will not be enabled. Additionally, for an analog input signal, in addition to the extra delay, a degradation in the lossy compression of the MPEG encoder and decoder in the PVR subsystem impairs the picture quality.
It would be advantageous to provide methods and apparatus which reduce the tune-time delay associated with the PVR subsystem, while still enabling trick play modes. It would also be advantageous to provide improved quality of analog channels. Further, it would be advantageous to optimize the most common use mode of the television appliance so that the PVR subsystem may be available to perform other tasks, such as video scaling, graphics, DOCSIS modem data processing, and the like.
The methods and apparatus of the present invention provide the foregoing and other advantages.